1
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Maryu G, Yang Q. Nuclear-cytoplasmic compartmentalization of cyclin B1-Cdk1 promotes robust timing of mitotic events. Cell Rep 2022; 41:111870. [PMID: 36577372 DOI: 10.1016/j.celrep.2022.111870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/15/2022] [Accepted: 12/01/2022] [Indexed: 12/28/2022] Open
Abstract
The cyclin-dependent kinase (Cdk1) oscillator is widely characterized in homogenized cytosolic extracts, leaving unclear the impact of nucleocytoplasmic compartmentalization. Here, by developing a Förster resonance energy transfer (FRET) biosensor, we track Cdk1 spatiotemporal dynamics in reconstituted cells with or without side by side and find compartmentalization significantly modulates clock properties previously found in bulk studies. Although nucleus-absent cells display highly tunable frequency, the nucleus-present cells maintain constant frequency against cyclin B1 variations. Despite high expression variability, cyclin degraded within the same duration, enabling a robust mitotic phase. Moreover, Cdk1 and cyclin B1 cycle rigorously out-of-phase, ensuring wide phase-plane orbits, essential for oscillation robustness. Although Cdk1 in homogeneous extracts is well known for delayed switch-like activation, we find active cyclin B1-Cdk1 accumulates in nuclei, without delay, until the nuclear envelope breakdown (NEB) when another abrupt activation triggers anaphase. Cdk1 biphasic activation and spatial compartmentalization may together coordinate the accurate ordering of different downstream events.
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Affiliation(s)
- Gembu Maryu
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Qiong Yang
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA; Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA.
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2
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Quantifying single-cell ERK dynamics in colorectal cancer organoids reveals EGFR as an amplifier of oncogenic MAPK pathway signalling. Nat Cell Biol 2021; 23:377-390. [PMID: 33795873 PMCID: PMC7610573 DOI: 10.1038/s41556-021-00654-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 02/24/2021] [Indexed: 02/07/2023]
Abstract
Direct targeting of the downstream mitogen-activated protein kinase (MAPK) pathway to suppress extracellular-regulated kinase (ERK) activation in KRAS and BRAF mutant colorectal cancer (CRC) has proven clinically unsuccessful, but promising results have been obtained with combination therapies including epidermal growth factor receptor (EGFR) inhibition. To elucidate the interplay between EGF signalling and ERK activation in tumours, we used patient-derived organoids (PDOs) from KRAS and BRAF mutant CRCs. PDOs resemble in vivo tumours, model treatment response and are compatible with live-cell microscopy. We established real-time, quantitative drug response assessment in PDOs with single-cell resolution, using our improved fluorescence resonance energy transfer (FRET)-based ERK biosensor EKAREN5. We show that oncogene-driven signalling is strikingly limited without EGFR activity and insufficient to sustain full proliferative potential. In PDOs and in vivo, upstream EGFR activity rigorously amplifies signal transduction efficiency in KRAS or BRAF mutant MAPK pathways. Our data provide a mechanistic understanding of the effectivity of EGFR inhibitors within combination therapies against KRAS and BRAF mutant CRC.
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3
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Pintard L, Archambault V. A unified view of spatio-temporal control of mitotic entry: Polo kinase as the key. Open Biol 2018; 8:180114. [PMID: 30135239 PMCID: PMC6119860 DOI: 10.1098/rsob.180114] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 07/29/2018] [Indexed: 12/18/2022] Open
Abstract
The Polo kinase is an essential regulator of cell division. Its ability to regulate multiple events at distinct subcellular locations and times during mitosis is remarkable. In the last few years, a much clearer mechanistic understanding of the functions and regulation of Polo in cell division has emerged. In this regard, the importance of coupling changes in activity with changes in localization is striking, both for Polo itself and for its upstream regulators. This review brings together several new pieces of the puzzle that are gradually revealing how Polo is regulated, in space and time, to enable its functions in the early stages of mitosis in animal cells. As a result, a unified view of how mitotic entry is spatio-temporally regulated is emerging.
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Affiliation(s)
- Lionel Pintard
- Cell Cycle and Development Team, Institut Jacques Monod, UMR7592 CNRS-Université Paris Diderot, Sorbonne Paris Cité, Ligue contre le Cancer, Paris, France
- Equipe labellisée, Ligue contre le Cancer, Paris, France
| | - Vincent Archambault
- Institut de recherche en immunologie et en cancérologie, Université de Montréal, Montréal, Québec, Canada
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4
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Kundrotas G, Gasperskaja E, Slapsyte G, Gudleviciene Z, Krasko J, Stumbryte A, Liudkeviciene R. Identity, proliferation capacity, genomic stability and novel senescence markers of mesenchymal stem cells isolated from low volume of human bone marrow. Oncotarget 2017; 7:10788-802. [PMID: 26910916 PMCID: PMC4905439 DOI: 10.18632/oncotarget.7456] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/05/2016] [Indexed: 12/16/2022] Open
Abstract
Human bone marrow mesenchymal stem cells (hBM-MSCs) hold promise for treating incurable diseases and repairing of damaged tissues. However, hBM-MSCs face the disadvantages of painful invasive isolation and limited cell numbers. In this study we assessed characteristics of MSCs isolated from residual human bone marrow transplantation material and expanded to clinically relevant numbers at passages 3-4 and 6-7. Results indicated that early passage hBM-MSCs are genomically stable and retain identity and high proliferation capacity. Despite the chromosomal stability, the cells became senescent at late passages, paralleling the slower proliferation, altered morphology and immunophenotype. By qRT-PCR array profiling, we revealed 13 genes and 33 miRNAs significantly differentially expressed in late passage cells, among which 8 genes and 30 miRNAs emerged as potential novel biomarkers of hBM-MSC aging. Functional analysis of genes with altered expression showed strong association with biological processes causing cellular senescence. Altogether, this study revives hBM as convenient source for cellular therapy. Potential novel markers provide new details for better understanding the hBM-MSC senescence mechanisms, contributing to basic science, facilitating the development of cellular therapy quality control, and providing new clues for human disease processes since senescence phenotype of the hematological patient hBM-MSCs only very recently has been revealed.
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Affiliation(s)
- Gabrielis Kundrotas
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania.,Biobank, National Cancer Institute, Vilnius, Lithuania
| | - Evelina Gasperskaja
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania
| | - Grazina Slapsyte
- Department of Botany and Genetics, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania
| | | | - Jan Krasko
- Laboratory of Immunology, National Cancer Institute, Vilnius, Lithuania
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5
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Kachaner D, Garrido D, Mehsen H, Normandin K, Lavoie H, Archambault V. Coupling of Polo kinase activation to nuclear localization by a bifunctional NLS is required during mitotic entry. Nat Commun 2017; 8:1701. [PMID: 29167465 PMCID: PMC5700101 DOI: 10.1038/s41467-017-01876-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/22/2017] [Indexed: 02/07/2023] Open
Abstract
The Polo kinase is a master regulator of mitosis and cytokinesis conserved from yeasts to humans. Polo is composed of an N-term kinase domain (KD) and a C-term polo-box domain (PBD), which regulates its subcellular localizations. The PBD and KD can interact and inhibit each other, and this reciprocal inhibition is relieved when Polo is phosphorylated at its activation loop. How Polo activation and localization are coupled during mitotic entry is unknown. Here we report that PBD binding to the KD masks a nuclear localization signal (NLS). Activating phosphorylation of the KD leads to exposure of the NLS and entry of Polo into the nucleus before nuclear envelope breakdown. Failures of this mechanism result in misregulation of the Cdk1-activating Cdc25 phosphatase and lead to mitotic and developmental defects in Drosophila. These results uncover spatiotemporal mechanisms linking master regulatory enzymes during mitotic entry. Drosophila Polo kinase is the founding member of the Polo-Like Kinase (PLK) family and a master regulator of mitosis and cytokinesis. Here the authors uncover a molecular mechanism for the spatiotemporal regulation of Polo kinase during mitotic entry through a phosphorylation event that triggers nuclear import.
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Affiliation(s)
- David Kachaner
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7.,Département de biochimie et médecine moléculaire, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Damien Garrido
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7.,Département de biochimie et médecine moléculaire, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Haytham Mehsen
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Karine Normandin
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Hugo Lavoie
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7
| | - Vincent Archambault
- Institute for Research in Immunology and Cancer, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7. .,Département de biochimie et médecine moléculaire, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC, Canada, H3C 3J7.
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6
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Wang R, Su C, Wang X, Fu Q, Gao X, Zhang C, Yang J, Yang X, Wei M. Global gene expression analysis combined with a genomics approach for the identification of signal transduction networks involved in postnatal mouse myocardial proliferation and development. Int J Mol Med 2017; 41:311-321. [PMID: 29115400 PMCID: PMC5746306 DOI: 10.3892/ijmm.2017.3234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 10/26/2017] [Indexed: 11/26/2022] Open
Abstract
Mammalian cardiomyocytes may permanently lose their ability to proliferate after birth. Therefore, studying the proliferation and growth arrest of cardiomyocytes during the postnatal period may enhance the current understanding regarding this molecular mechanism. The present study identified the differentially expressed genes in hearts obtained from 24 h-old mice, which contain proliferative cardiomyocytes; 7-day-old mice, in which the cardiomyocytes are undergoing a proliferative burst; and 10-week-old mice, which contain growth-arrested cardiomyocytes, using global gene expression analysis. Furthermore, myocardial proliferation and growth arrest were analyzed from numerous perspectives, including Gene Ontology annotation, cluster analysis, pathway enrichment and network construction. The results of a Gene Ontology analysis indicated that, with increasing age, enriched gene function was not only associated with cell cycle, cell division and mitosis, but was also associated with metabolic processes and protein synthesis. In the pathway analysis, 'cell cycle', proliferation pathways, such as the 'PI3K-AKT signaling pathway', and 'metabolic pathways' were well represented. Notably, the cluster analysis revealed that bone morphogenetic protein (BMP)1, BMP10, cyclin E2, E2F transcription factor 1 and insulin like growth factor 1 exhibited increased expression in hearts obtained from 7-day-old mice. In addition, the signal transduction pathway associated with the cell cycle was identified. The present study primarily focused on genes with altered expression, including downregulated anaphase promoting complex subunit 1, cell division cycle (CDC20), cyclin dependent kinase 1, MYC proto-oncogene, bHLH transcription factor and CDC25C, and upregulated growth arrest and DNA damage inducible α in 10-week group, which may serve important roles in postnatal myocardial cell cycle arrest. In conclusion, these data may provide important information regarding myocardial proliferation and development.
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Affiliation(s)
- Ruoxin Wang
- Department of Cardiovascular Surgery, Tianjin Medical University General Hospital, Tianjin 300070, P.R. China
| | - Chao Su
- Department of Biochemistry and Molecular Biology, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Xinting Wang
- Department of Biochemistry and Molecular Biology, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Qiang Fu
- Department of Cardiovascular Surgery, Tianjin Medical University General Hospital, Tianjin 300070, P.R. China
| | - Xingjie Gao
- Department of Biochemistry and Molecular Biology, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Chunyan Zhang
- Department of Biochemistry and Molecular Biology, Department of Immunology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Jie Yang
- Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
| | - Xi Yang
- Department of Immunology, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
| | - Minxin Wei
- Department of Cardiovascular Surgery, Tianjin Medical University General Hospital, Tianjin 300070, P.R. China
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7
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Mitutsova V, Yeo WWY, Davaze R, Franckhauser C, Hani EH, Abdullah S, Mollard P, Schaeffer M, Fernandez A, Lamb NJC. Adult muscle-derived stem cells engraft and differentiate into insulin-expressing cells in pancreatic islets of diabetic mice. Stem Cell Res Ther 2017; 8:86. [PMID: 28420418 PMCID: PMC5395782 DOI: 10.1186/s13287-017-0539-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/16/2017] [Indexed: 12/12/2022] Open
Abstract
Background Pancreatic beta cells are unique effectors in the control of glucose homeostasis and their deficiency results in impaired insulin production leading to severe diabetic diseases. Here, we investigated the potential of a population of nonadherent muscle-derived stem cells (MDSC) from adult mouse muscle to differentiate in vitro into beta cells when transplanted as undifferentiated stem cells in vivo to compensate for beta-cell deficiency. Results In vitro, cultured MDSC spontaneously differentiated into insulin-expressing islet-like cell clusters as revealed using MDSC from transgenic mice expressing GFP or mCherry under the control of an insulin promoter. Differentiated clusters of beta-like cells co-expressed insulin with the transcription factors Pdx1, Nkx2.2, Nkx6.1, and MafA, and secreted significant levels of insulin in response to glucose challenges. In vivo, undifferentiated MDSC injected into streptozotocin (STZ)-treated mice engrafted within 48 h specifically to damaged pancreatic islets and were shown to differentiate and express insulin 10–12 days after injection. In addition, injection of MDSC into hyperglycemic diabetic mice reduced their blood glucose levels for 2–4 weeks. Conclusion These data show that MDSC are capable of differentiating into mature pancreatic beta islet-like cells, not only upon culture in vitro, but also in vivo after systemic injection in STZ-induced diabetic mouse models. Being nonteratogenic, MDSC can be used directly by systemic injection, and this potential reveals a promising alternative avenue in stem cell-based treatment of beta-cell deficiencies. Electronic supplementary material The online version of this article (doi:10.1186/s13287-017-0539-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Violeta Mitutsova
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France
| | - Wendy Wai Yeng Yeo
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France.,Genetics & Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Romain Davaze
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France
| | - Celine Franckhauser
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France
| | - El-Habib Hani
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France
| | - Syahril Abdullah
- Genetics & Regenerative Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Patrice Mollard
- Networks and Rhythms in Endocrine Glands, IGF, CNRS UMR-5203, Montpellier, France
| | - Marie Schaeffer
- Networks and Rhythms in Endocrine Glands, IGF, CNRS UMR-5203, Montpellier, France
| | - Anne Fernandez
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France.
| | - Ned J C Lamb
- Mammalian Cell Biology group, IGH CNRS, UM, UMR 9002, 141 rue de la Cardonille, 34396, Montpellier cedex 05, France.
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8
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Phosphatases and kinases regulating CDC25 activity in the cell cycle: clinical implications of CDC25 overexpression and potential treatment strategies. Mol Cell Biochem 2016; 416:33-46. [PMID: 27038604 DOI: 10.1007/s11010-016-2693-2] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Accepted: 03/24/2016] [Indexed: 10/22/2022]
Abstract
Alterations in the cell-cycle regulatory genes result in uncontrolled cell proliferation leading to several disease conditions. Cyclin-dependent kinases (CDK) and their regulatory subunit, cyclins, are essential proteins in cell-cycle progression. The activity of CDK is regulated by a series of phosphorylation and dephosphorylation at different amino acid residues. Cell Division Cycle-25 (CDC25) plays an important role in transitions between cell-cycle phases by dephosphorylating and activating CDKs. CDC25B and CDC25C play a major role in G2/M progression, whereas CDC25A assists in G1/S transition. Different isomers of CDC25 expressions are upregulated in various clinicopathological situations. Overexpression of CDC25A deregulates G1/S and G2/M events, including the G2 checkpoint. CDC25B has oncogenic properties. Binding to the 14-3-3 proteins regulates the activity and localization of CDC25B. CDC25C is predominantly a nuclear protein in mammalian cells. At the G2/M transition, mitotic activation of CDC25C protein occurs by its dissociation from 14-3-3 proteins along with its phosphorylation at multiple sites within its N-terminal domain. In this article, we critically reviewed the biology of the activation/deactivation of CDC25 by kinases/phosphatases to maintain the level of CDK-cyclin activities and thus the genomic stability, clinical implications due to dysregulation of CDC25, and potential role of CDC25 inhibitors in diseases.
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9
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Abstract
The centrosome was discovered in the late 19th century when mitosis was first described. Long recognized as a key organelle of the spindle pole, its core component, the centriole, was realized more than 50 or so years later also to comprise the basal body of the cilium. Here, we chart the more recent acquisition of a molecular understanding of centrosome structure and function. The strategies for gaining such knowledge were quickly developed in the yeasts to decipher the structure and function of their distinctive spindle pole bodies. Only within the past decade have studies with model eukaryotes and cultured cells brought a similar degree of sophistication to our understanding of the centrosome duplication cycle and the multiple roles of this organelle and its component parts in cell division and signaling. Now as we begin to understand these functions in the context of development, the way is being opened up for studies of the roles of centrosomes in human disease.
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Affiliation(s)
- Jingyan Fu
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
| | - Iain M Hagan
- Cancer Research UK Manchester Institute, University of Manchester, Withington, Manchester M20 4BX, United Kingdom
| | - David M Glover
- Cancer Research UK Cell Cycle Genetics Group, Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom
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10
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Khammanivong A, Wang C, Sorenson BS, Ross KF, Herzberg MC. S100A8/A9 (calprotectin) negatively regulates G2/M cell cycle progression and growth of squamous cell carcinoma. PLoS One 2013; 8:e69395. [PMID: 23874958 PMCID: PMC3706396 DOI: 10.1371/journal.pone.0069395] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 06/14/2013] [Indexed: 12/16/2022] Open
Abstract
Malignant transformation results in abnormal cell cycle regulation and uncontrolled growth in head and neck squamous cell carcinoma (HNSCC) and other cancers. S100A8/A9 (calprotectin) is a calcium-binding heterodimeric protein complex implicated in cell cycle regulation, but the specific mechanism and role in cell cycle control and carcinoma growth are not well understood. In HNSCC, S100A8/A9 is downregulated at both mRNA and protein levels. We now report that downregulation of S100A8/A9 correlates strongly with a loss of cell cycle control and increased growth of carcinoma cells. To show its role in carcinogenesis in an in vitro model, S100A8/A9 was stably expressed in an S100A8/A9-negative human carcinoma cell line (KB cells, HeLa-like). S100A8/A9 expression increases PP2A phosphatase activity and p-Chk1 (Ser345) phosphorylation, which appears to signal inhibitory phosphorylation of mitotic p-Cdc25C (Ser216) and p-Cdc2 (Thr14/Tyr15) to inactivate the G2/M Cdc2/cyclin B1 complex. Cyclin B1 expression then downregulates and the cell cycle arrests at the G2/M checkpoint, reducing cell division. As expected, S100A8/A9-expressing cells show both decreased anchorage-dependent and -independent growth and mitotic progression. Using shRNA, silencing of S100A8/A9 expression in the TR146 human HNSCC cell line increases growth and survival and reduces Cdc2 inhibitory phosphorylation at Thr14/Tyr15. The level of S100A8/A9 endogenous expression correlates strongly with the reduced p-Cdc2 (Thr14/Tyr14) level in HNSCC cell lines, SCC-58, OSCC-3 and UMSCC-17B. S100A8/A9-mediated control of the G2/M cell cycle checkpoint is, therefore, a likely suppressive mechanism in human squamous cell carcinomas and may suggest new therapeutic approaches.
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Affiliation(s)
- Ali Khammanivong
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Chengxing Wang
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Brent S. Sorenson
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Karen F. Ross
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Mucosal and Vaccine Research Center, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Mark C. Herzberg
- Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Mucosal and Vaccine Research Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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11
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Purification and biochemical analysis of catalytically active human cdc25C dual specificity phosphatase. Biochimie 2013; 95:1450-61. [DOI: 10.1016/j.biochi.2013.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 03/22/2013] [Indexed: 11/18/2022]
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12
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Wei D, Parsels LA, Karnak D, Davis MA, Parsels JD, Marsh AC, Zhao L, Maybaum J, Lawrence TS, Sun Y, Morgan MA. Inhibition of protein phosphatase 2A radiosensitizes pancreatic cancers by modulating CDC25C/CDK1 and homologous recombination repair. Clin Cancer Res 2013; 19:4422-32. [PMID: 23780887 DOI: 10.1158/1078-0432.ccr-13-0788] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE To identify targets whose inhibition may enhance the efficacy of chemoradiation in pancreatic cancer and thus improve survival, we conducted an siRNA library screen in pancreatic cancer cells. We investigated PPP2R1A, a scaffolding subunit of protein phosphatase 2A (PP2A) as a lead radiosensitizing target. EXPERIMENTAL DESIGN We determined the effect of PP2A inhibition by genetic (PPP2R1A siRNA) and pharmacologic (LB100, a small molecule entering phase I clinical trials) approaches on radiosensitization of Panc-1 and MiaPaCa-2 pancreatic cancer cells both in vitro and in vivo. RESULTS PPP2R1A depletion by siRNA radiosensitized Panc-1 and MiaPaCa-2 cells, with radiation enhancement ratios of 1.4 (P < 0.05). Likewise, LB100 produced similar radiosensitization in pancreatic cancer cells, but minimal radiosensitization in normal small intestinal cells. Mechanistically, PPP2R1A siRNA or LB100 caused aberrant CDK1 activation, likely resulting from accumulation of the active forms of PLK1 (pPLK1 T210) and CDC25C (pCDC25C T130). Furthermore, LB100 inhibited radiation-induced Rad51 focus formation and homologous recombination repair (HRR), ultimately leading to persistent radiation-induced DNA damage, as reflected by γ-H2AX expression. Finally, we identified CDC25C as a key PP2A substrate involved in LB100-mediated radiosensitization as depletion of CDC25C partially reversed LB100-mediated radiosensitization. In a mouse xenograft model of human pancreatic cancer, LB100 produced significant radiosensitization with minimal weight loss. CONCLUSIONS Collectively, our data show that PP2A inhibition radiosensitizes pancreatic cancer both in vitro and in vivo via activation of CDC25C/CDK1 and inhibition of HRR, and provide proof-of-concept evidence that PP2A is a promising target for the improvement of local therapy in pancreatic cancer.
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Affiliation(s)
- Dongping Wei
- Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan 48109-5637, USA
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13
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Senille V, Lelievre D, Paquet F, Garnier N, Lamb N, Legrand A, Delmas AF, Landon C. The addressing fragment of mitogaligin: first insights into functional and structural properties. Chembiochem 2013; 14:711-20. [PMID: 23532929 DOI: 10.1002/cbic.201200715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Indexed: 11/07/2022]
Abstract
Mitogaligin is a mitochondrion-targeting protein involved in cell death. The sequence of the protein is unrelated to that of any known pro- or antiapoptotic protein. Mitochondrial targeting is controlled by an internal sequence from residues 31 to 53, and although this sequence is essential and sufficient to provoke cell death, the precise mechanism of action at the mitochondrial membrane remains to be elucidated. Here, by focusing on the [31-53] fragment, we first assessed and confirmed its cell cytotoxicity by microinjection. Subsequently, with the aid of membrane models, we evaluated the impact of the membrane environment on the 3D structure of the peptide and on how the peptide is embedded and oriented within membranes. The fragment is well organized, even though it does not contain a canonical secondary structure, and adopts an interfacial location. Structural comparison with other membrane-interacting Trp-rich peptides demonstrated similarities with the antimicrobial peptide tritrpcidin.
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Affiliation(s)
- Violette Senille
- Centre de Biophysique Moléculaire, CNRS UPR4301 affiliated to the University of Orléans, Rue Charles Sadron, 45071 Orléans cedex 2, France
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